Hi Pavel, > We have to set ctx->sq_thread_idle before adding a ring to an SQ task, > otherwise sqd races for seeing zero and accounting it as such. > > Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx> > --- > fs/io_uring.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/fs/io_uring.c b/fs/io_uring.c > index 896a7845447c..0b39c3818809 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -7827,14 +7827,14 @@ static int io_sq_offload_create(struct io_ring_ctx *ctx, > > ctx->sq_creds = get_current_cred(); > ctx->sq_data = sqd; > - io_sq_thread_park(sqd); > - list_add(&ctx->sqd_list, &sqd->ctx_new_list); > - io_sq_thread_unpark(sqd); > - > ctx->sq_thread_idle = msecs_to_jiffies(p->sq_thread_idle); > if (!ctx->sq_thread_idle) > ctx->sq_thread_idle = HZ; > > + io_sq_thread_park(sqd); > + list_add(&ctx->sqd_list, &sqd->ctx_new_list); > + io_sq_thread_unpark(sqd); I wondered about the exact same change this morning, while researching the IORING_SETUP_ATTACH_WQ behavior :-) It still seems to me that IORING_SETUP_ATTACH_WQ changed over time. As you introduced that flag, can you summaries it's behavior (and changes) over time (over the releases). I'm wondering if ctx->sq_creds is really the only thing we need to take care of. Do we know about existing users of IORING_SETUP_ATTACH_WQ and their use case? As mm, files and other things may differ now between sqe producer and the sq_thread. metze
